The present invention relates to the field of small wheeled vehicles, and more specifically, it is concerned with a self-propelled wheelbarrow driven without the use of a motor or electric power.
Laborers in a variety of industries frequently use wheelbarrows and carts to manually move heavy or awkward loads about a work site. For example, in commercial settings construction workers may use wheelbarrows to transport supplies, waste debris, mixed concrete, and other materials as needed from point to point. In private settings, landscapers and gardeners may use wheelbarrows to aid in transporting rocks, soil and potting material, and other tools from a supply location to a work site.
The wheelbarrow has been known in one form or another since early civilization. It generally consists of a carrying enclosure such as a tub or box supported by two parallel handles, the handles being supported by the axis of a wheel serving as a fulcrum on one end and being lifted and pushed by a person holding the opposing end. The single wheel allows the load in the tub to be pushed and easily maneuvered along the ground around challenging obstacles. The size of the load carried in this manner is limited by the ability of the person pushing the wheelbarrow to vertically lift the load mass and then to apply horizontal force to cause the wheelbarrow to roll about its wheel axis along the ground. The horizontal force required to move the loaded wheelbarrow can be increased by obstacles on the ground that impede the rolling action of the wheel (such as rocks, ridges, uneven ground, tools, etc.) or grades. Engines and motors have sometimes been added to the wheelbarrow structure to assist the wheelbarrow user in moving the wheelbarrow horizontally over these obstacles and grades by applying an additional, cooperative driving force to the wheels.
For example, U.S. Pat. No. 6,390,213, issued to Bleicher, discloses a self-propelled cart powered by motors that power independent drive wheels so that each wheel thus equipped with its own motor assists the user in moving the cart over rough or uneven surfaces. The motors are powered by electrical means such as batteries. U.S. Pat. No. 2,918,133, issued to Ericsson, discloses a barrow or cart also propelled by a gasoline-powered engine driving a single front axle having dual wheels.
Such modifications as adding engines and motors to the basic wheelbarrow configuration greatly assist the user in moving heavy loads. However, there are a number of drawbacks to such arrangements. First, motors and engines are generally more expensive than the wheelbarrow structure itself. When factoring in the cost of buying a whole new wheelbarrow along with the assisting mechanisms, the expense becomes even more cumbersome. Second, engines and motors are heavy and bulky and contribute to the weight of the combined wheelbarrow structure and load. Third, the use of the engine or motor imposes a requirement to have a readily available source of fuel. In the case of an engine, gasoline or some other such volatile liquid must be provided; in the case of a motor, the battery must be recharged when it is depleted. In either case, the fuel source must accompany the wheelbarrow or cart when using the apparatus in a remote area. Fourth, use of engines and motors increases the complexity of the apparatus. Engines in particular must be maintained and serviced at periodic intervals. Fifth, an engine is frequently noisy and creates air pollution from the exhaust fumes.
Thus, it can be seen that there is a need for an wheelbarrow apparatus to assist the user in moving heavy loads around obstacles and up steep grades, the apparatus being inexpensive, simple to maintain, lighter than standard motors and engines, quiet, nonpolluting, and requiring a readily available or renewable source of fuel. It can also be seen that such technology should be available to retrofit existing wheelbarrows to reduce the cost of redundantly purchasing the wheelbarrow itself.
The present invention achieves its intended purposes, objects, and advantages through a new, useful, and unobvious combination of component elements, with the use of a minimum number of functioning parts, at a reasonable cost to manufacture, and by employing only readily available materials. In these respects, the present version of the invention substantially departs from the conventional concepts and designs of the prior art, and in so doing provides an apparatus that substantially fulfills this need. Additionally, the prior patents and commercial techniques do not suggest the present inventive combination of component elements arranged and configured as disclosed herein.
In one aspect of the invention, a spring powered drive apparatus is provided for a vehicle having at least one wheel. The apparatus is comprised of a drive assembly and a braking assembly. The drive assembly is further comprised of a drive spring for storing and releasing rotational force, crank for manually applying manual rotational force to the drive spring, a first power transmission means to transmit the rotational force applied to the crank to the drive spring for storage of rotational energy, and a second power transmission means to transmit the stored rotational force to a wheel of the vehicle. The braking assembly allows an operator selectively to prevent movement of the wheel or to allow the wheel to rotate freely under the urging of the second power transmission means.
In another aspect of the invention, a manually powered vehicle is provided for a vehicle with at least one wheel rotating on an axle. The vehicle has a drive assembly comprising an drive spring supported on a spring shaft by a fixed hub at a first end of the drive spring and a movable hub at a second end of the drive spring, with the fixed hub arranged to restrain rotational movement of the drive spring and the movable hub arranged to allow rotational movement of the drive spring. A manually powered crank is provided along with a first drive means disposed to communicate rotational force provided by movement of the crank to the movable hub in a direction that winds the drive spring and a second drive means disposed to communicate the stored rotational force exerted by the drive spring on the movable hub to the wheel. A braking assembly is also provided for selectively preventing rotational movement of the wheel and allowing the wheel to rotate freely.
In another aspect of the invention, the present invention provides a wheelbarrow with a manually powered drive assembly, the wheelbarrow comprising a load bearing container, a frame with rails supporting the container at a distance from a horizontal surface, rails positioned intermediate the front and back ends and a transversely mounted wheel positioned at the front end. The drive assembly features a drive assembly frame affixed to the underside of the load bearing container, the frame transversely and fixedly supporting a spring shaft. A drive spring is transversely mounted over the spring shaft, the drive spring positioned under the load bearing container. A drive shaft supports a crank sprocket, transversely supported by and rotating within the drive assembly frame. The drive shaft is manually rotated by foot crank located on the right end of the drive shaft, as viewed from the handle area of the apparatus. The crank sprocket is connected by a first power transmission means to a spring sprocket on the spring shaft. The spring shaft rotates the drive spring, extending or elongating the drive spring against a spring hub, the spring hub guided along spring keepers. The drive spring has a first end constrained from rotational movement and a second end rigidly connected to a rotating hub axially supported by the spring shaft. Thus, an incremented turn of the pedal extends the drive spring so that the drive spring unwinds from its natural position and builds potential energy. Elongate handles are engaged to elevate the rails of the frame at a distance from a horizontal surface. The elongate handles span a back end of the apparatus to a front end of the apparatus substantially under the container. A handle has a hand brake comprising a vertically oriented lever, a brake rod passing below the container and above the frame, and a brake shoe connected to the brake rod so that the plate rubs upon a front wheel and frictionally holds the apparatus in a dormant state. The apparatus moves upon release of a locking pin on the hand brake, disengaging the friction plate from the front wheel. As the locking pin is released, the drive spring returns to its original position, rotating the spring shaft and the spring sprocket in an opposite direction, turning a second power transmission means connected to the freewheel sprocket at the front of the apparatus by a drive chain. The freewheel sprocket rotates a wheel shaft, which turns the wheel so that forward motion of the apparatus is accomplished.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be made to the accompanying drawings and descriptive matter in which there are illustrated preferred embodiments of the invention. The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent feature and applications of the present invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or by modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention and the detailed description of the preferred embodiments in addition to the scope of the invention illustrated by the accompanying drawings.